dm mpath: add optional "queue_mode" feature
Allow a user to specify an optional feature 'queue_mode <mode>' where
<mode> may be "bio", "rq" or "mq" -- which corresponds to bio-based,
request_fn rq-based, and blk-mq rq-based respectively.
If the queue_mode feature isn't specified the default for the
"multipath" target is still "rq" but if dm_mod.use_blk_mq is set to Y
it'll default to mode "mq".
This new queue_mode feature introduces the ability for each multipath
device to have its own queue_mode (whereas before this feature all
multipath devices effectively had to have the same queue_mode).
This commit also goes a long way to eliminate the awkward (ab)use of
DM_TYPE_*, the associated filter_md_type() and other relatively fragile
and difficult to maintain code.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index a682d51..88f0174 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -43,8 +43,10 @@
struct dm_target *targets;
struct target_type *immutable_target_type;
- unsigned integrity_supported:1;
- unsigned singleton:1;
+
+ bool integrity_supported:1;
+ bool singleton:1;
+ bool all_blk_mq:1;
/*
* Indicates the rw permissions for the new logical
@@ -206,6 +208,7 @@
return -ENOMEM;
}
+ t->type = DM_TYPE_NONE;
t->mode = mode;
t->md = md;
*result = t;
@@ -703,7 +706,7 @@
dm_device_name(t->md), type);
return -EINVAL;
}
- t->singleton = 1;
+ t->singleton = true;
}
if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {
@@ -830,16 +833,29 @@
table_type == DM_TYPE_MQ_REQUEST_BASED);
}
-static int dm_table_set_type(struct dm_table *t)
+void dm_table_set_type(struct dm_table *t, unsigned type)
+{
+ t->type = type;
+}
+EXPORT_SYMBOL_GPL(dm_table_set_type);
+
+static int dm_table_determine_type(struct dm_table *t)
{
unsigned i;
unsigned bio_based = 0, request_based = 0, hybrid = 0;
- bool use_blk_mq = false;
+ bool verify_blk_mq = false;
struct dm_target *tgt;
struct dm_dev_internal *dd;
- struct list_head *devices;
+ struct list_head *devices = dm_table_get_devices(t);
unsigned live_md_type = dm_get_md_type(t->md);
+ if (t->type != DM_TYPE_NONE) {
+ /* target already set the table's type */
+ if (t->type == DM_TYPE_BIO_BASED)
+ return 0;
+ goto verify_rq_based;
+ }
+
for (i = 0; i < t->num_targets; i++) {
tgt = t->targets + i;
if (dm_target_hybrid(tgt))
@@ -876,6 +892,19 @@
BUG_ON(!request_based); /* No targets in this table */
+ if (list_empty(devices) && __table_type_request_based(live_md_type)) {
+ /* inherit live MD type */
+ t->type = live_md_type;
+ return 0;
+ }
+
+ /*
+ * The only way to establish DM_TYPE_MQ_REQUEST_BASED is by
+ * having a compatible target use dm_table_set_type.
+ */
+ t->type = DM_TYPE_REQUEST_BASED;
+
+verify_rq_based:
/*
* Request-based dm supports only tables that have a single target now.
* To support multiple targets, request splitting support is needed,
@@ -888,7 +917,6 @@
}
/* Non-request-stackable devices can't be used for request-based dm */
- devices = dm_table_get_devices(t);
list_for_each_entry(dd, devices, list) {
struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
@@ -899,10 +927,10 @@
}
if (q->mq_ops)
- use_blk_mq = true;
+ verify_blk_mq = true;
}
- if (use_blk_mq) {
+ if (verify_blk_mq) {
/* verify _all_ devices in the table are blk-mq devices */
list_for_each_entry(dd, devices, list)
if (!bdev_get_queue(dd->dm_dev->bdev)->mq_ops) {
@@ -910,14 +938,9 @@
" are blk-mq request-stackable");
return -EINVAL;
}
- t->type = DM_TYPE_MQ_REQUEST_BASED;
- } else if (list_empty(devices) && __table_type_request_based(live_md_type)) {
- /* inherit live MD type */
- t->type = live_md_type;
-
- } else
- t->type = DM_TYPE_REQUEST_BASED;
+ t->all_blk_mq = true;
+ }
return 0;
}
@@ -961,9 +984,9 @@
return __table_type_request_based(dm_table_get_type(t));
}
-bool dm_table_mq_request_based(struct dm_table *t)
+bool dm_table_all_blk_mq_devices(struct dm_table *t)
{
- return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED;
+ return t->all_blk_mq;
}
static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
@@ -1106,7 +1129,7 @@
return 0;
if (!integrity_profile_exists(dm_disk(md))) {
- t->integrity_supported = 1;
+ t->integrity_supported = true;
/*
* Register integrity profile during table load; we can do
* this because the final profile must match during resume.
@@ -1129,7 +1152,7 @@
}
/* Preserve existing integrity profile */
- t->integrity_supported = 1;
+ t->integrity_supported = true;
return 0;
}
@@ -1141,9 +1164,9 @@
{
int r;
- r = dm_table_set_type(t);
+ r = dm_table_determine_type(t);
if (r) {
- DMERR("unable to set table type");
+ DMERR("unable to determine table type");
return r;
}